As an evolution of 3G technology, the LTE improves and enhances the 3G air access technology. A new generation wireless network based on Orthogonal Frequency Division Multiplexing (OFDM) and Multiple-Input Multiple-Output (MIMO) technologies can provide a peak rate of 100 Mbit/s in downlink and 50 Mbit/s in uplink under a spectrum bandwidth of 20 MHz, thereby improving the performance of cell edge users, increasing the cell capacity and spectrum utilization ratio, and reducing the system delay. In terms of system architecture, the LTE makes an evolution on the basis of the original system architecture of 3rd Generation Partnership Project (3GPP), and integrates and simplifies functions of a NodeB, a Radio Network Controller (RNC) and a Core Network (CN). In the system architecture of the LTE, the system equipment consists of two parts: an Evolved NodeB (eNB) and an Evolved Packet Core (EPC).
For a downlink traffic channel in the LTE, the sending flow at the eNB side is as shown in FIG. 1 and comprises: Cyclic Redundancy Check (CRC), code block segmentation, Turbo coding, rate matching, code block concatenation, scrambling, modulation, layer mapping, pre-coding, resource mapping and OFDM symbol generation; the receiving flow at the UE side is as shown in FIG. 2 and comprises: reception of antenna data, demodulation of OFDM symbol, demodulation of MIMO symbol, demodulation, descrambling, de-code-block concatenation, de-rate matching, Hybrid Automatic Repeat Request (HARQ) combination and channel decoding or the like.
Each code block corresponds to one rate matching module, and the input of each rate matching is the output of the Turbo coding module, i.e., parallel three branches: dk(0), dk(1) and dk(2) (k=0, . . . , K−1). In terms of structure, the rate matching module comprises: three interleaver sub-modules for respectively processing the three branches, one bit collection sub-module for summarization and one bit selection and reduction sub-module. Three branches of data are read-in in lines by respective independent sub-block interleavers, redundant nulls are filled in the front of the interleaving matrix, and data are read-out in columns after being exchanged in columns. Then, the three branches of interleaved data are summarized to the bit collection sub-module, the first branch of data is input in turn, and the second branch of data and the third branch of data are placed alternately. Finally, from k0, the redundant nulls in the data in the bit collection sub-module are skipped, and E valid data are selected in turn as the output of the rate matching.
As an inverse process of the rate matching, the de-rate matching comprises three processes: de-puncturing, de-interleaving and de-repeating, wherein the de-repeating is an optional process. The specific implementations of the above three processes are as follows:
de-puncturing: nulls taken out during the bit selection and reduction process of the rate matching are filled into the valid data;
de-interleaving: it is an inverse process of the sub-block interleaving;
de-repeating: the rate matching starts from k0, if the valid data after k0 cannot fill the length E of ek, the rate matching will cycle to start from the start part until ek is filled.
As the length E of ek is determined according to the situation of resource allocation, there may be not integral number of times of cycle when ek is generated, therefore, during the implementation, it is necessary to acquire the number of times of cycle of each radio frame for generation of ek during the rate matching (obtained by E/Nc, wherein Nc refers to the number of valid data after k0) and information about the remaining bits after integral number of times of cycle. Then, each piece of soft information is averaged according to the cycle period, and then the averaged data is de-punctured or de-interleaved.
In the conventional art, the de-rate matching is an important processing process for downlink traffic channel. In the current technologies, there are very few de-rate matching methods for a downlink traffic channel at the terminal side in the LTE. According to the present de-rate matching method related to the 3G and the LTE, the received code blocks are de-rate matched in only one manner, the method is relatively single and is lack of flexibility, and the complexity of implementation is relatively high.